#include <stdio.h>
#include <string.h>

int mycmp(const char* s1, const char* s2)
{
	while ( *s1++ == *s2++ && *s1 != '\0') {

	}
	return *--s1 - *--s2;
}
int main(int argc, char const *argv[]){
	char s1[] = "abc";
	char s2[] = "abc";
	printf("%d\n", mycmp(s1,s2));
	return 0;
}
